Broaching tool



Oct. 21, 1941. K. BAKE BROACHING TOQL 1 Filed Jan. 18, 1940 J nvenfor:

E K A B T M K H'Hcrrneys:

Patented Oct. 21, 1941 UNITED STATE s PATENT OFFICE- BROACHING 'rooL Kurt Bake, Zerbst, Anhalt, Germany, assignor to Junkers Flugzeng-und-Motorenwerke, A. G., Dessau, Dessan, Germany, a corporation of Germany Application January 18, 1940, Serial No. 914,419 a In Germany December 13, 1938 3 Claims.

This invention relates to breaching machines and refers more particularly to a device for guiding and holding the breaching tool of such machines.

Broaching machines comprise usually a.

breaching tool or a breaching needle, which is vide a breaching machine of this type which is so constructed that the scraping edges of the breaching tool are maintained in a'predetermined angular relationship to theworkpiece in .the course of the entire movement of the tool through the workpiece.

Anotherobject is the provision of a simple and eifectiveoperating means for firmly holding a breaching tool in the course of its movement through a workpiece from a tool feeder to a receiver.

Other objects of the present invention will become apparent in the course of the following specification.

The objects of the present'invention may be realized through the provision of means provided in the tool feeder as well as the tool receiver,

' which look the breaching tool in a perpendicular plane in such manner that it occupies in the 'course of its movement a predetermined crosssectional position relatively to the workpiece which is also secured against turningin relation to the tool receiver;

The invention will appear more clearly from faces 6 of the tool 3.

sleeve 4 in a cavity. 9 provided within the tool down, as indicated by thearrews a in Figure 1. The feeder i carries the breaching tool or breaching needle -3. The feeder l'is hollow and its inner cavity 2 contains a sleeve 4 provided with inner conical surfaces .5, constituting a conical bore hole which may receivethe end sur- The tool 3 and the sleeve 4 are so constructed that the tool 3 is supported by the tool feeder I when the end surfaces 6 of the tool are in engagement with the conical surfaces 5 of the sleeve 4.

- The tool 3 .is provided with an end I which is substantially flat and-rectangular in cross-section, as shown in Figure 3, and which issituated at a distance from the end surfaces 6. The

parallel fiat surfaces of the end I- extend at 'a predetermined radial angle to the operative scraping edges 24 of the tool 3.

Two wide leaf springs 8 are situated below the feeder I- The springs 8 are located oppositeeach other and are held by bolts carried by another sleeve which is situated within the tool feeder I and is screwed thereto. The distance between adjacent ends of the springs 8 is such that-the springs 8 can receive the end 'I and hold it firm? ly while the tool 3 is moved by the tool feeder l in the directions of the arrow 0 (Figures 1 and 3).

The tool receiver Ill is situated above. the tool feeder I and is coaxial therewith. The receiver 80 is so connected with the machine frame that it' can also move vertically in the directions of the following detailed description when taken in connection with the accompanying drawing showing, by way of example, a preferred embodiment of the inventive idea.

In the drawing:

Figure 1 is alongitudinal section through a device constructed in accordance with the principles of the-present invention, some parts being-shown in side elevation; I

Figure 2 is a cross-section along the line 11-11 of Figure l; and

.Flgure 3 is a cross-section along the 'line III-III of Figure 1.

The device shown-in the drawing constitutes a part of a broaching machine the frame of which is not illustrated. This. frame is conthe arrow 11. That end of the receiver III which is situated close to the feeder I carries an insert or sleeve II which is connected by pins or other suitable mea'nsto the receiver III. The sleeve N is provided with'a central conicalbore hole I2 which has the form of a trough so that it can receive conveniently an end of the tool 3.

As shown in Figures 1 and 2, a tight fitting spring I4 is connected by a belt with the sleeve El and has a projecting'end l3 which issituated within the bore hole I 2.

,When the tool 3 is situated in the position shown in Figure 1', the end I3 of the spring I4 projects into a longitudinal groove I5 which is provided in the upper end of the tool 3. The

the tool 3 should'be equal to the angle between a tool engaging surface of a spring 8 inthe tool feeder l and the end l3 of the spring I4 provided in the tool receiver III. I

manner that the feeder I' can move up and 5 The tool receiver I0. carries adjusting screws I6 (Figure 2) which are used to maintain the sleeve II and the spring I4 carried thereby in the required position relatively to the tool holder III. This position is such that the guiding means 8 for the lower end I of the tool 3 in the feeder I corresponds circumferentially to the position of the guiding means I3 in the receiver Ill, and that, therefore, no turning of the tool 3 can take place when the tool is moved from the feeder to the receiver.

Two locking bars I! are used to' hold the tool 3 in the receiver-III (Figure 1). The bars H are movably mounted in suitable openings provided in the receiver I and are operated by springs which are not shown in the drawing. In the locking position shown in Figure 1, the bars project into corresponding cavities I8 provided in the tool 3. A removable and replaceable support 20 is screwed by bolts to a plate I 9 constituting a. part of the machine frame and is located between the tool feeder I and the tool holder ID. The support 2Ii is used for holding the workpiece 22 and is provided with a cut out portion 2|, the outline of which should correspond exactly to the outline of the workpiece 22, so that the workpiece 22 fits into the cut out.

portion 2I. Thus the workpiece 22 is prevented from turning and is firmly held in a predetermined position relatively to the support 20. Consequently, the position of the support 2ll is precisely determined relatively to the machine frame, the feeder I, the tool 3. The device is operated as follows: The tool feeder I which carries the tool 3 is the receiver III, as well as moved upwardly and introduces the upper end of the tool 3 into the opening 23.which has been previously formed in the workpiece 22. Theup per end of the tool 3 is moved through the workpiece 22 and is introduced into the troughiike opening I2 of the sleeve II carried by the tool receiver III.

In the course of this movement, the springs 8 maintain the tool 3 in the required predetermined position relatively to the feeder As already stated, the position of the springs 8 cor responds exactly to the. position of the spring I4 the conical opening 5 of the sleeve 4 which is carried by the tool feeder I. p

The springs 8 are so disposed in relation to the sleeve surfaces 5, and the tool surfaces 6 are so arranged relatively to the end I of the tool, that the fiat end 1 of the tool 3 comes into engagement with the springs 8 before the surfaces 6 of the tool are engaged by the surfaces 5 of the sleeve 4. Due to this arrangement, the tool 3 turns, if necessary, to assume its proper position within the feeder I before it is brought to rest in the conical opening 5. The tool 3 is thus caused to occupy the required position, so that in the course of the next operation, the end I3 of the spring I4 is situated precisely in the path of the groove I5 of the tool.

As has been already stated, the support 20 isa replaceable one and is carried by the plate I9 of the machine frame. That side of the support 20 which faces the feeder I is provided with a cut-out portion 2|, the outline of which corresponds exactly to the outline of the workpiece 22. The workpiece 22 is fitted into the cut-out portion M and is held therein by hand by the operator until the tool 3 is moved by the feeder I through the hole of the workpiece 22, the support 20, and the plate I9, and until the tool 3 is held by the-.receiver I0. Then the operator can release his hold upon the workpiece 22, since the upward movement of the tool 3 will hold the workpiece 22 in its position within the cut-out portion 2I until the operation is completed.

' Shortly before the. completion of the operation,

the operator should grip again the workpiece 22 until the last scraping edges of the tool have moved beyond the hole of the workpiece. Then the workpiece is removed by the operator. Thereupon the tool 3 is freed, so that it will drop out of theholder I0 and into the feeder I. The

operator inserts a new workpiece into the cut-out portion 2|, and then the operation can be repeated.

It is apparent that due to the described arposition in relation to the-workpiece -22 during carried by the sleeve I I in relation to the tool receiver I0, and the fiat surfaces of the end I are correspondingly located, so that no turning of the tool can takeplace during this movement. Therefore, during the penetration of the upper end of the tool 3 into the receiver III, the projecting and I3 of the spring I! is introduced into the groove I5 of the tool 3. Due to-this arrangement, the scraping edges 24 of the tool 3 aremaintained in an exactly predeterminable circumferential position relatively to the workpiece 22. Y

The introduction of the tool 3 into the receiver I0 is terminated when thetwo locking bars I! are moved into the recesses I8 of the tool under the action of springs which are not shown in the drawing. Then the tool 3is held firmly by.

the tool receiver I0 so that the scraping opera tion can begin.

Simultaneously, the lower end 6 of the tool 3 is pulled out of the tool feeder I, so that the tool 3 is then held solely by the tool receiver III. Then the tool receiver Ill pulls the tool 3 through the'workpiece 22 causing the scraping edges 24 to carry out their work. Then the workpiece 22 is removed and the bars II are moved outwardly, freeing the tool 3, which drops out of the holder ID. The lower end 6 of the tool 3 is received in the entire operation of the machine. The teeth or scraping edges 24 remove shavings, the positions of which relatively to theform of the workpiece 22 are exactly determined.

This device is particularly advantageous when several workpieces are to be subjected to the same scraping operation, since all the surfaces treated by the scraping edges will occupy the same positions.

It is apparent that the specific illustrations shown above and the terms and expressions employed herein have been used by way of lllus- I I tration and not by way of limitation and that 3 with a movable tool feeder and a tool receiver;

a broaching tool movable along with said toolfeeder relatively to a workpiece, and means for preventing the workpiece from turning-relatively to the tool receiver, said tool feeder having resilient tool-engaging means, said tool receiver comprising tool holding means, said breaching tool comprising a substantially fiat end engaged by the-resilient tool-engaging means of workpiece from turning relatively to the tool,

receiver, said tool feeder having resilient toolengaging means and means spaced" therefrom and constitutinga support for an end surface of the tool; said tool receiver comprising tool holding means, said broaching tool comprising a substantially flat end spaced from said end surface to cause the resilient tool-engaging means to engage said flat end before said end surface is engaged by said support, said tool also having a portion engaged by the tool holding means of said tool receiver to maintain the tool in a predetermined cross-section position relatively to the workpiece;

.of said tool feeder and the tool holding means 3. In a breaching machine, in combination, with a movable tool feeder and a tool receiver; a broaching tool-movable along with said tool feeder relatively to a workpiece, and means for preventing the workpiece from turning relatively to the tool receiver, said tool feeder and said tool receiver comprising tool holding means, said broaching tool comprising a substantially flat end engaged by the tool holding means of said tool feeder, said broaching tool also having a guiding groove formed therein which is engaged by the'tool holding means of said tool receiver, the radial angle between said guiding groove and said flat .end being substantially equal to the radial angle between the tool holding means of said tool receiver. a KURT BAKE. 

